ISO 17331:2004 表面化学分析—シリコンウェーハ加工標準材料の表面から元素を収集するための化学的方法および全反射蛍光X線（TXRF）分光法によるそれらの決定 | ページ 2

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights (see Note to 10.1). ISO shall not be held responsible for identifying any or all such patent rights.

ISO 17331 was prepared by Technical Committee ISO/TC 201, Surface chemical analysis.

Introduction

The measurement of metal impurities on the surface of silicon wafers by total-reflection X-ray fluorescence spectroscopy (TXRF) is commonly accepted by the semiconductor industry.

ISO 14706 specifies a TXRF method for the measurement of metal impurities on a silicon-wafer surface with atomic surface densities from 1 × 10¹⁰ atoms/cm² to 1 × 10¹⁴ atoms/cm², also a vapour-phase decomposition (VPD) method for atomic surface densities from 5 × 10⁸ atoms/cm² to 5 × 10¹² atoms/cm².

In ultra-large-scale integrated circuit (ULSI) manufacturing, the measurement of very-low-level metal impurities on the surface of a silicon wafer, less than 10¹⁰ atoms/cm², is currently required.

Reference materials with low-level metal impurities are important in TXRF analysis (see ISO 14706), but the reference materials have a limited shelf life, especially as regards surface contamination. As a result, preparation methods for working reference materials need to be standardized.

This test method allows the calculation of metal impurities on the surface of reference and test wafers. Interlaboratory trials in nine laboratories in different countries indicated that this method has good reproducibility and repeatability.

1 Scope

This International Standard specifies chemical methods for the collection of iron and/or nickel from the surface of silicon-wafer working reference materials by the vapour-phase decomposition method or the direct acid droplet decomposition method.

This International Standard applies to iron and/or nickel atomic surface densities from 6 × 10⁹ atoms/cm² to 5 × 10¹¹ atoms/cm².

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.